H2O2 Yield Research Articles

High‐rate electrochemical H2O2 production over multimetallic atom catalysts under acidic–neutral conditions

AbstractHydrogen peroxide (H2O2) production by the electrochemical 2‐electron oxygen reduction reaction (2e− ORR) is a promising alternative to the energy‐intensive anthraquinone process, and single‐atom electrocatalysts show the unique capability of high selectivity toward 2e− ORR against the 4e− one. The extremely low surface density of the single‐atom sites and the inflexibility in manipulating their geometric/electronic configurations, however, compromise the H2O2 yield and impede further performance enhancement. Herein, we construct a family of multiatom catalysts (MACs), on which two or three single atoms are closely coordinated to form high‐density active sites that are versatile in their atomic configurations for optimal adsorption of essential *OOH species. Among them, the Cox–Ni MAC presents excellent electrocatalytic performance for 2e− ORR, in terms of its exceptionally high H2O2 yield in acidic electrolytes (28.96 mol L−1 gcat.−1 h−1) and high selectivity under acidic to neutral conditions in a wide potential region (>80%, 0–0.7 V). Operando X‐ray absorption and density functional theory analyses jointly unveil its unique trimetallic Co2NiN8 configuration, which efficiently induces an appropriate Ni–d orbital filling and modulates the *OOH adsorption, together boosting the electrocatalytic 2e− ORR capability. This work thus provides a new MAC strategy for tuning the geometric/electronic structure of active sites for 2e− ORR and other potential electrochemical processes.

Enhanced photochemical degradation and transformation of ciprofloxacin in a UV/calcium peroxide system: pH effects, defluorination kinetics, and different components numerical analysis

Advanced oxidation processes (AOPs) are highly efficient for the removal of antibiotics from water. The activation of hydrogen peroxide (H2O2) by ultraviolet (UV) has garnered increasing attention. This study describes the enhanced photochemical degradation of emerging contaminants in water using a UV-activated calcium peroxide (UV/CaO2) system, wherein CaO2 can gently produce H2O2 when exposed to UV light. The UV/CaO2 system can expeditiously and efficiently eradicate ciprofloxacin (CIP), in which hydroxyl radicals (•OH) and superoxide anions (O2•-) played critical roles. The superlative rate constant was 0.024 min−1 at an optimal dosage of 0.1 g L−1, which was a 16-fold increase over the rate of pure UV photolysis. The UV/CaO2 system had an excellent defluorination capacity (80% within 60 min). Further, this technology was intensely evaluated over a wide range of pH for the removal of CIP, including H2O2 yields, defluorination rates, as well as correlations with the reactive species generated during the reactions for numerical analysis. The UV/CaO2 system had an excellent anti-interference capacity over a wide pH range. Three major degradation pathways were proposed for the degradation of CIP, together with predictions of the physiological toxicity of these transformation intermediates. This study provides strong technical support for the promotion of this UV/CaO2 water treatment platform, as well as the decontamination and defluorination of water matrixes contaminated with fluoroquinolones.

Enhancing piezocatalytic H2O2 production through morphology control of graphitic carbon nitride

Piezocatalytic H2O2 production has attracted significant attention as a green alternative to traditional anthraquinone methods with heavy environmental pollution and high energy consumption. However, since the efficiency of piezocatalyst in producing H2O2 is poor, searching for a suitable method to improve the yield of H2O2 is of great interest. Herein, a series of graphitic carbon nitride (g-C3N4) with different morphologies (hollow nanotube, nanosheet and hollow nanosphere) are applied to enhance the piezocatalytic performance in yielding H2O2. The hollow nanotube g-C3N4 exhibited an outstanding H2O2 generation rate of 262 umol·g−1·h−1 without any co-catalyst, which is 1.5 and 6.2 times higher than nanosheets and hollow nanospheres, respectively. Piezoelectric response force microscopy, piezoelectrochemical tests, and Finite Element Simulation results revealed that the excellent piezocatalytic property of hollow nanotube g-C3N4 is mainly attributed to its larger piezoelectric coefficient, higher intrinsic carrier density, and stronger external stress absorption conversion. Furthermore, mechanism analysis indicated that piezocatalytic H2O2 production follows a two-step single-electro pathway, and the discovery of 1O2 furnishes a new insight into explore this mechanism. This study offers a new strategy for the eco-friendly manufacturing of H2O2 and a valuable guide for future research on morphological modulation in piezocatalysis.

Controlled synthesis of hollow carbon ring incorporated g-C3N4 tubes for boosting photocatalytic H2O2 production

H2O2 production through solar-driven photocatalytic route has received increasing attention. Herein, a carbon ring incorporated hollow g-C3N4 tubes (CHCN) was successfully fabricated via a novel supramolecular self-assembly strategy, co-inducing by hydrogen bond and covalent bond. The optimum H2O2 yield over the CHCN-0.02 reached up to 1.58 mmol L−1 h−1 (AQE= 28.10%, 420 nm), which was 5.4 times significantly higher than that of bulk g-C3N4 (0.29 mmol L−1 h−1) under visible light irradiation. Experimental and density functional theory (DFT) calculations revealed that the CHCNs not only expedited the charge carrier transfer/separation but also favored molecular oxygen adsorption and regulated bandgap structure under the in-plane electronic field induced by continuous π-conjugated Cring, which boosted the ORR efficiency for photocatalytic H2O2 synthesis. The optimized CHCN catalyst demonstrated adequate hybrid ORR routes, consisting of a dominated selective one-step two-electron ORR pathway and highly efficient two-step single-electron ORR for H2O2 production. Therefore, this work not only provides a new strategy for an efficient H2O2 formation using a g-C3N4-based photocatalyst but also explores the functionary mechanism of the ORR process and enlightens the way to highly efficient H2O2 generation.

Monte Carlo study of the free radical yields in minibeam radiation therapy.

Minibeam radiation therapy (MBRT) is a novel technique which has been shown to widen the therapeutic window through significant normal tissue sparing. Despite the heterogeneous dose distributions, tumor control is still ensured. Nevertheless the exact radiobiological mechanisms responsible for MBRT efficacy are not fullyunderstood. Reactive oxygen species (ROS) resulting from water radiolysis were investigated given their implications not only on targeted DNA damage, but also for their role in the immune response and non-targeted cell signalling effects: two potential drivers of MBRTefficacy. Monte Carlo simulations were performed using TOPAS-nBio to carry out the irradiation of a water phantom with beams of protons (pMBRT), photons (xMBRT), 4 He ions (HeMBRT), and 12 C ions (CMBRT). Primary yields at the end of the chemical stage were calculated in spheres of 20 μm diameter, located in the peaks and valleys at various depths up to the Bragg peak. The chemical stage was limited to 1 ns to approximate biological scavenging, and the yield of · OH, H2 O2 , and wasrecorded. Beyond 10 mm, there were no substantial differences in the primary yields between peaks and valleys of the pMBRT and HeMBRT modalities. For xMBRT, there was a lower primary yield of the radical species · OHand at all depths in the valleys compared to the peaks, and a higher primary yield of H2 O2 . Compared to the peaks, the valleys of the CMBRT modality were subject to a higher · OHand yield, and lower H2 O2 yield. This difference between peaks and valleys became more severe in depth. Near the Bragg peak, the increase in the primary yield of the valleys over the peaks was 6% and 4% for · OH and respectively, while there was a decrease in the yield of H2 O2 by 16%. Given the similar ROS primary yields in the peaks and valleys of pMBRT and HeMBRT, the level of indirect DNA damage is expected to be directly proportional to the peak to valley dose ratio (PVDR). The difference in the primary yields implicates a lower level of indirect DNA damage in the valleys compared to the peaks than what would be suggested by the PVDR for xMBRT, and a higher level for CMBRT. These results highlight the notion that depending on the particle chosen, one can expect different levels of ROS in the peaks and valley that goes beyond what would be expected by the macroscopic PVDR. The combination of MBRT with heavier ions is shown to be particularly interesting as the primary yield in the valleys progressively diverges from the level observed in the peaks as the LET increases. While differences in the reported · OH yields of this work implicated the indirect DNA damage, H2 O2 yields particularly implicate non-targeted cell signalling effects, and therefore this work provides a point of reference for future simulations in which the distribution of this species at more biologically relevant timescales could beinvestigated.

CdS decorated resorcinol–formaldehyde spheres as an inorganic/organic S-scheme photocatalyst for enhanced H2O2 production

Photocatalytic H2O2 production provides a clean and sustainable strategy for artificial photosynthesis. Herein, an inorganic/organic composite photocatalyst was fabricated by in-situ growth of CdS nanoparticles on the surface of resorcinol–formaldehyde (RF) resin spheres. RF spheres played multiple roles: (i) acting as a substrate for the growth of CdS and constructing a core-shell structure with seamless contact; (ⅱ) improving visible light absorption of CdS; (ⅲ) forming an S-scheme heterojunction with CdS and promoting the charge separation and transfer. Consequently, under visible light illumination, CdS/RF composite presented remarkably enhanced H2O2 production activity. Its H2O2 yield in 60 min was 801 μmol L–1, which was 5.2 and 1.5 times higher than that of RF spheres and CdS hollow spheres, respectively. The charge migration between CdS and RF followed the S-scheme photocatalytic mechanism, which was verified by work function measurement, ex-situ and in-situ irradiated X-ray photoelectron spectroscopy. This work brings a novel insight into designing RF-based inorganic/organic S-scheme heterojunction photocatalysts for efficient H2O2 production.

Cyano-rich porous carbon nitride nanosheets for enhanced photocatalytic H2O2 production

The gas template method is used to introduce the cyano (-CN) group and porous thin-layer structure into g-C3N4 simultaneously. The resulting material exhibits a synergistic effect between the -CN group and porous thin-layer structure, which broadens the optical absorption range of g-C3N4 and enhances electron transfer and transformation. The rotating ring-disk electrode (RRDE) experiments demonstrate that cyano-rich porous ultrathin carbon nitride significantly improves the selectivity of 2e- oxygen reduction reaction (ORR), with the selectivity of 93% compared to the 66% of the original carbon nitride at a potential of 0.3 V versus RHE. Additionally, the H2O2 yield for the modified carbon nitride is twice than that of the original carbon nitride material (99.11 μM vs 49.79 μM). The mechanism for photocatalytic H2O2 production involves a two-step one-electron reaction. The modified catalyst is recyclable and can be used for an extended period of time. Overall, this study provides a viable method for modifying g-C3N4 to improve its photocatalytic activity and selectivity towards the 2e- ORR.

Visible-Light Photocatalytic CO2-to-CO and H2O-to-H2O2 by g-C3N4/Cu2O-Pd S-Scheme Heterojunctions.

Visible-light photocatalytic conversion of CO2-to-fuels for green electricity is sustainably attractive for alleviating carbon emissions. Photocatalytic CO2-to-CO frequently suffered from relatively low yields, mainly due to ineffective charge transfer rates. A new approach for photocatalytic CO2-to-CO enhanced with effective H+ from H2O-to-H2O2 through the water oxidation reaction (WOR) has been studied in the present work. Here, the nano palladium (9 wt %), serving as a cocatalyst, dispersed on the g-C3N4/Cu2O heterojunctions (i.e., g-C3N4/Cu2O-Pd) has been prepared to facilitate charge separation for the two-electron reduction of CO2 to CO. Experimentally, the g-C3N4/Cu2O-Pd heterojunctions have a higher photocatalytic H2O-to-H2O2 yield than the g-C3N4/Cu2O heterojunction by 5.3 times. The photocatalytic WOR provides sufficient electrons (e-) and H+ (2H2O → H2O2 + 2H+) for CO2-to-CO (CO2(aq) + 2H+ + 2e- → CO(g) + H2O(l)). Relatively high photocatalytic yields of H2O2 (34.0 μmol/mg) and CO (14.6 μmol/mg) affected by the heterojunctions can be achieved. Also, the heterojunctions have a high photostability with a photocatalytic generated CO/H2 ratio of 1.75 approximately. This visible-light photocatalytic CO2-to-CO and H2O-to-H2O2 by the new g-C3N4/Cu2O-Pd S-scheme heterojunctions demonstrates the feasibility of the zero carbon emission approach with additional green oxidant (H2O2) generation.

Sulfone-Modified Covalent Organic Frameworks Enabling Efficient Photocatalytic Hydrogen Peroxide Generation via One-Step Two-Electron O2 Reduction.

Photocatalytic oxygen reduction reaction (ORR) offers a promising hydrogen peroxide (H2 O2 ) synthetic strategy, especially the one-step two-electron (2e- ) ORR route holds great potential in achieving highly efficient and selectivity. However, efficient one-step 2e- ORR is rarely harvested and the underlying mechanism for regulating the ORR pathways remains greatly obscure. Here, by loading sulfone units into covalent organic frameworks (FS-COFs), we present an efficient photocatalyst for H2 O2 generation via one-step 2e- ORR from pure water and air. Under visible light irradiation, FS-COFs exert a superb H2 O2 yield of 3904.2 μmol h-1 g-1 , outperforming most reported metal-free catalysts under similar conditions. Experimental and theoretical investigation reveals that the sulfone units accelerate the separation of photoinduced electron-hole (e- -h+ ) pairs, enhance the protonation of COFs, and promote O2 adsorption in the Yeager-type, which jointly alters the reaction process from two-step 2e- ORR to the one-step one, thereby achieving efficient H2 O2 generation with high selectivity.

S-Scheme Heterojunction Photocatalysts for H2O2 Production.

Photocatalysis opens a new door to H2O2 formation via a low-cost, clean, mild, and sustainable process, which holds great promise for the next generation of massive H2O2 production. However, fast photogenerated electron-hole recombination and slow reaction kinetics are the main obstacles for its practical application. An effective solution is to construct the step-scheme (S-scheme) heterojunction, which remarkably promotes carrier separation and boosts the redox power for efficient photocatalytic H2O2 production. Considering the superiority of S-scheme heterojunctions, this Perspective summarizes the recent advances of S-scheme photocatalysts for H2O2 production, including photocatalysts for building S-scheme heterojunctions, H2O2-production performance, and S-scheme photocatalytic mechanisms. Lastly, some prospects are given to motivate future research in this promising field, other promising strategies are provided to further improve H2O2 yields, and future research directions are suggested.

Sulfone‐Modified Covalent Organic Frameworks Enabling Efficient Photocatalytic Hydrogen Peroxide Generation via One‐Step Two‐Electron O2 Reduction

AbstractPhotocatalytic oxygen reduction reaction (ORR) offers a promising hydrogen peroxide (H2O2) synthetic strategy, especially the one‐step two‐electron (2e−) ORR route holds great potential in achieving highly efficient and selectivity. However, efficient one‐step 2e− ORR is rarely harvested and the underlying mechanism for regulating the ORR pathways remains greatly obscure. Here, by loading sulfone units into covalent organic frameworks (FS‐COFs), we present an efficient photocatalyst for H2O2 generation via one‐step 2e− ORR from pure water and air. Under visible light irradiation, FS‐COFs exert a superb H2O2 yield of 3904.2 μmol h−1 g−1, outperforming most reported metal‐free catalysts under similar conditions. Experimental and theoretical investigation reveals that the sulfone units accelerate the separation of photoinduced electron‐hole (e−‐h+) pairs, enhance the protonation of COFs, and promote O2 adsorption in the Yeager‐type, which jointly alters the reaction process from two‐step 2e− ORR to the one‐step one, thereby achieving efficient H2O2 generation with high selectivity.

Multi-Functional Bio-HJzyme: Revolutionizing Diabetic Skin Regeneration with its Glucose-Unlocked Sterilization and Programmed Anti-Inflammatory Effects.

Antibacterial dynamic therapy (ADT) triggered by reactive oxygen species (ROS) is promising for diabetic infectious disease treatment. However, the limited local O2 /H2 O2 production and post-treatment inflammation remain long-standing issues. To address these challenges, a novel H2 -evolving bio-heterojunction enzyme (Bio-HJzyme) consisting of graphite-phase carbon nitride/copper sulfide (CN/Cu2-x S) heterojunction and glucose oxidase (GOx) is created. The Bio-HJzyme offers glutathione peroxidase (GPx), peroxidase (POD), and catalase (CAT) mimetic activities; provides anti-pathogen properties via programmed light activation; and effectively promotes diabetic wound healing. Specifically, its GPx-mimetic activity and the presence of GOx significantly enhance the yield of H2 O2 , which can be catalyzed through POD-mimetic activity to produce highly germicidal •OH. The H2 O2 can also be catalyzed to H2 O and O2 , assisted by the CAT-mimetic activity. The catalyzed products can then be catalyzed into germicidal •OH and •O2 - under NIR light irradiation, giving enhanced ADT. Further, CN can split water to form H2 under solar light, which dramatically suppresses the inflammation caused by excessive ROS. In vivo evaluation confirms that Bio-HJzyme promotes the regeneration of diabetic infectious skin through killing bacteria, enhancing angiogenesis, promoting wound bed epithelialization, and reinforcing anti-inflammatory responses; hence, providing a revolutionary approach for diabetic wounds healing.

Synergistic effects of Bi2O3 and Ta2O5 for efficient electrochemical production of H2O2

Electrochemical oxygen reduction reaction (ORR) through a two-electron pathway has been provided a green route for on-site hydrogen peroxide (H2O2) production. Developing high-selective electrocatalysts for H2O2 production are urgently sought. Herein, a m-Bi2O3/Ta2O5 electrocatalyst (m: “Bi” mass contents) has been successfully synthesized by simple physical mixing associated with an outstanding selectivity towards H2O2 (94.7%), over 10% higher than Ta2O5 (80.9%) and Bi2O3 (81.7%). 10-Bi2O3/Ta2O5 also exhibits 471 mmol/(gcat·h) H2O2 yield with 91.8% Faraday Efficiency. The in-situ generated H2O2 can function as disinfection agent for efficiently deactivating model bacteria (e.g., Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli) within 30 min. In-situ Raman and DFT proposed the synergistic effects of Bi2O3 and Ta2O5 in boosting 2e- ORR performance. In this work, it not only presents a high-selective electrocatalyst for 2e- ORR, but also provides a new idea for electrocatalyst design from the perspective of reaction process.

A Pentagonal Defect-Rich Metal-Free Carbon Electrocatalyst for Boosting Acidic O2 Reduction to H2O2 Production

Metal-free carbon-based materials are considered one of the most promising two-electron oxygen reduction reaction (2e- ORR) electrocatalysts for the green synthesis of hydrogen peroxide (H2O2). However, most reported carbon electrocatalysts perform much more effectively in alkalis than in acids. Herein, by creatively using fullerene (C60) as the precursor subject to ammonia treatment, we designed and synthesized a pentagonal defect-rich nitrogen-doped carbon nanomaterial (PD/N-C). It achieves outstanding ORR activity, 2e- selectivity, and stability in acidic electrolytes, surpassing the benchmark PtHg4 alloy catalyst. Impressively, the flow cell based on the PD/N-C catalyst achieves nearly 100% Faraday efficiency with a remarkable H2O2 yield, representing the best improvement among all the metal-free catalysts. Experimental and theoretical results reveal that such superb 2e- ORR performance of PD/N-C originates from the synergism between pentagonal defects and nitrogen dopants. This work presents an effective strategy for the design and construction of highly efficient acid-resistant carbon electrocatalysts for H2O2 production and beyond.

Cu0@CuOx-NC modified Zn2In2S5 for photo-self-Fenton system coupling H2O2 in-situ production and decomposition

Although many concerns have been put into photocatalytic hydrogen peroxide (H2O2) production, multifunctional catalysis suitable for continuously in-situ H2O2 consumption in the field has rarely been investigated. Herein, Cu0@CuOx@nitrogen-doped graphitic carbon (Cu0@CuOx-NC) decorated Zn2In2S5 was successfully prepared for in-situ production and activation H2O2, which could achieve effectively photocatalytic self-Fenton degradation of tetracycline (TC). Under visible light irradiation, 5 wt% Cu0@CuOx-NC/Zn2In2S5 (CuZS-5) efficiently generated a high yield of H2O2 (0.13 mmol L−1), and Cu0@CuOx-NC could in-situ consume H2O2 to generate hydroxyl radicals (•OH), accelerating the oxidation of TC. As a result, the 5 wt% Cu0@CuOx-NC/Zn2In2S5 degraded about 89.3% of TC within 60 min, and the cycle experiments also exhibited sufficient stability. This study achieves a delicate combination of in-situ production and activation of H2O2, which is regarded as a promising strategy to eco-friendly promote pollutant degradation in wastewater.

Ultrahigh Performance H2 O2 Generation by Single-Atom Fe Catalysts with N/O Bidentate Ligand via Oxalic Acid and Oxygen Molecules Activation.

Single-atom catalysts (SACs) for photocatalytic hydrogen peroxide (H2 O2 ) generation are researched but it is still challenging to obtain high H2 O2 yields. Herein, graphite carbon nitride (FeSA /CN) confined single Fe atoms with N/O coordination is prepared, and FeSA /CN shows high H2 O2 production via oxalic acid and O2 activation. Under visible light illumination, the concentration of H2 O2 generated by FeSA /CN can achieve 40.19mM g-1 h-1 , which is 10.44 times higher than that of g-C3 N4 . The enhanced H2 O2 generation can be attributed to the formation of metal-organic complexes and rapid electron transfer. Moreover, the O2 activation of photocatalysts is revealed by 3,3',5,5'-tetramethylbenzidine oxidation. The results display that the O2 activation capacity of FeSA /CN is higher than that of g-C3 N4 , which facilitates the formation of H2 O2 . Finally, density functional theory calculation demonstrates that O2 is chemically adsorbed on Fe atomic sites. The adsorption energy of O2 is enhanced from -0.555 to -1.497eV, and the bond length of OO is extended from 1.235 to 1.292 Å. These results exhibit that the confinement of single Fe atoms can promote O2 adsorption and activation. Finally, the photocatalytic mechanism is elaborated, which provides a deep understanding for SACs-catalyzed H2 O2 generation.

Carbon Black‐Supported Single‐Atom CoNC as an Efficient Oxygen Reduction Electrocatalyst for H2O2 Production in Acidic Media and Microbial Fuel Cell in Neutral Media

AbstractSingle metal atom isolated in nitrogen‐doped carbon materials (MNC) are effective electrocatalysts for oxygen reduction reaction (ORR), which produces H2O2 or H2O via 2‐electron or 4‐electron process. However, most of MNC catalysts can only present high selectivity for one product, and the selectivity is usually regulated by complicated structure design. Herein, a carbon black‐supported CoNC catalyst (CB@CoNC) is synthesized. Tunable 2‐electron/4‐electron behavior is realized on CB@Co‐N‐C by utilizing its H2O2 yield dependence on electrolyte pH and catalyst loading. In acidic media with low catalyst loading, CB@CoNC presents excellent mass activity and high selectivity for H2O2 production. In flow cell with gas diffusion electrode, a H2O2 production rate of 5.04 mol h−1 g−1 is achieved by CB@CoNC on electrolyte circulation mode, and a long‐term H2O2 production of 200 h is demonstrated on electrolyte non‐circulation mode. Meanwhile, CB@CoNC exhibits a dominant 4‐electron ORR pathway with high activity and durability in pH neutral media with high catalyst loading. The microbial fuel cell using CB@CoNC as the cathode catalyst shows a peak power density close to that of benchmark Pt/C catalyst.

Ambient Preparation of Benzoxazine‐based Phenolic Resins Enables Long‐term Sustainable Photosynthesis of Hydrogen Peroxide

AbstractRational design of polymer structures at the molecular level promotes the iteration of high‐performance photocatalyst for sustainable photocatalytic hydrogen peroxide (H2O2) production from oxygen and water, which also lays the basis for revealing the reaction mechanism. Here we report a benzoxazine‐based m‐aminophenol‐formaldehyde resin (APFac) polymerized at ambient conditions, exhibiting superior H2O2 yield and long‐term stability to most polymeric photocatalysts. Benzoxazine structure was identified as the crucial photocatalytic active segment in APFac. Favorable adsorption of oxygen/intermediates on benzoxazine structure and commendable product selectivity accelerated the reaction kinetically in stepwise single‐electron oxygen reduction reaction. The proposed benzoxazine‐based phenolic resin provides the possibility of production in batches and industrial application, and sheds light on the de novo design and analysis of metal‐free polymeric photocatalysts.

Ambient Preparation of Benzoxazine-based Phenolic Resins Enables Long-term Sustainable Photosynthesis of Hydrogen Peroxide.

Rational design of polymer structures at the molecular level promotes the iteration of high-performance photocatalyst for sustainable photocatalytic hydrogen peroxide (H2 O2 ) production from oxygen and water, which also lays the basis for revealing the reaction mechanism. Here we report a benzoxazine-based m-aminophenol-formaldehyde resin (APFac) polymerized at ambient conditions, exhibiting superior H2 O2 yield and long-term stability to most polymeric photocatalysts. Benzoxazine structure was identified as the crucial photocatalytic active segment in APFac. Favorable adsorption of oxygen/intermediates on benzoxazine structure and commendable product selectivity accelerated the reaction kinetically in stepwise single-electron oxygen reduction reaction. The proposed benzoxazine-based phenolic resin provides the possibility of production in batches and industrial application, and sheds light on the de novo design and analysis of metal-free polymeric photocatalysts.

Manipulation of the PdAu‒PdAuOx interface on Pd-Au bimetallic catalysts for the direct synthesis of hydrogen peroxide

Direct synthesis of H2O2 from H2 and O2via heterogeneous catalysis is an environmentally friendly and atomically economic alternative to the traditional anthraquinone oxidation (AO) process. Optimizing the electronic and geometric structures of the active metals to break the current limitations of hydrogenation rate and H2O2 selectivity is a promising and challenging topic. In this study, a series of Pd-Au bimetallic catalysts supported on TiO2 with a metal loading of 3.0 wt% and a constant Pd/Au molar ratio (Pd:Au = 2:1) were prepared. The catalysts were reduced in H2 at different temperatures (473, 573 and 673 K), and their catalytic activity for the direct H2O2 synthesis were evaluated at 283 K and 0.1 MPa. H2 reduced Pd-Au catalysts exhibited superior performance in direct H2O2 synthesis. The maximum H2O2 selectivity of 87.7% and H2O2 yield of 3116.4 mmol h−1 gPd−1 were achieved over the Pd2.0Au1.0-573 catalyst with a H2 conversion of 12.8%. The tailored local chemical environment caused by H2 reduction creates a balanced ratio of Pd0 and PdOx sites, thus improving the selectivity towards H2O2. This work developed an effective strategy for fabrication of highly active and stable Pd-based H2O2 synthesis catalysts with high H2O2 yield.